Spraying process and apparatus



Jne 24, 1941./ M POPQFF ,Y 2,247,009

SPRAYING PROCESS AND APPARATUS Filed May 15, 1939 Patented June 24, 1.941

2,247,000 SPRAYING PROCESS AND APPARATUS [Mintscho Popoff, Berlin,l Germany Application May 13, V1939, Serial No. 273,535

In Germany May 28, 1938 zo claims. (ol. 29e-14o) This invention relates to a new method and apparatus for spraying fluids such as paints and varnishes onto surfaces, wherein the fluid is atomized by means of a gas, such as air;

In devices of this type lthe higher the relative velocity of the liquid to air, the ner are the drops resulting from the atomization of .the liquid in the gas. The uniformity of the atomization depends on the uniformity of the air velocity in the air atomization range. Also kinetic energy is necessary for'delivering the atomized fluid on .the surface and this can be attained only through high flow velocity. On the separation of the `drops from the air current in the vicinity of the surface being sprayed, the more flnely di- .vided drops, by reason of their small masses, are

diverted by the air passing to the side and are lost in the form of a paint mist for the greater part. nate such loss.`

In known methods and apparatuses, the atomization and the depositing of the liquid is accompliched by one and the same air jet. higher velocity of the -airjet is necessary for the depositing of the atomized liquid, it necessarily follows that with this high velocity it is impossible vto avoid the formation of the ilner drops of liquid. However, as pointed out above these liner drops cannot be deposited on the surface to be painted. They are diverted by the air jet and passed oif/in/ the'V form of`mist` causing quite c'onsiderable loss of material and in addition is dangerous to health. It is. an object of the inven tion .to correct the above disadvantages.

An object of the present inventiontherefore is to provide a new method of operation wherein a jet is formed by the union of an atomizlng It is an object of the invention to elimi-v SlIlCe a stream passed through one or more atomizing nozzles and a depositing jet having a considerably greater velocity and passed, .through'one or more other nozzles adjacent the discharge point of the first jet. t I

A further object of the invention is to provide a construction wherein the conditions for the atomization and the depositing of the atomized liquid may be independently controlled so that the] most favorable conditions may be selected for each operation,

A still further object of the invention is to provide a method and apparatus wherein the formation of .the finer drops tending to form a mist are eliminated.

A still further object is to provide a construction and method of operation which Will positively assure the deposition of all of the liquid particles on the surface to be sprayed. y

A further object of the invention is to provide a method and construction in which a relatively low, uniformly distributed air velocity prevails so that approximately uniform drops of a desired size are obtained.

A still further object of .the vinvention is to provide a. construction in which a depositing stream of air or gas is provided which tends to positively apply all of the atomlzed particles t the surface being sprayed.

Heretofore spray nozzles have been constructed which consist of an inner atomizing nozzle producing the liquid-air mixture and an outer nozzleencompassing the inner nozzle. The inner nozzle therefore .terminates within the outer nozzle, In these prior constructions an air jet passed from the inner nozzle which serves to atomize as well as deposit lthe-atomized liquid. In

these constructions the outer nozzle merely forms an air jet to impart a predetermined form to the currentpassing from the inner nozzle, greatly accelerated and thus strongly permeated with line mist-forming drops. It is an object to eliminate this.

An object of the present invention is to provide a construction in which the mouth of the atomizing nozzle'is located in the direction of flow, in front of the mouth of the outer nozzle which serves as the depositing nozzle. The position of the mouth of the outer nozzle, as well as the discharge velocity of the depositing air, `as well as the quantity thereof, are so co-ordinated that the addition acceleration of the liquid drops already present remains within limits suc-.lr that secondary atomization does not take place.

In the atomizing nozzle is preferably disposed a rectier, which prevents turbulence of the atomizing air entering into the atomizing nozzle, and precludes rotational movements of the atomizing air in the nozzle. A similar rectifier can also be interposed in .the depositing nozzle. The rectiiier can be constructed in simple manner'as an annular screen. I

A still further object of theinvention is to Provide a construction in which the needle valve controlling the feed of the paint 'or varnish opens towards the nozzle mouth. As a result of this construction the needle valve may easily be removed from the nozzle at the front for cleaning.

In the 'construction according to the invention, the air passing to the atomizing nozzle and the depositing nozzle may be .'taken from a common source of compressed air or from separate Yappear from the detailed description below, the

invention is illustrated in the drawing, in which: i

Fig. l-is a longitudinal cross-sectional View through a paint spray pistol with the spraying head screwed thereon.

Fig. 2 is a longitudinal section through a modifled construction of spraying head which can be screwed on the pistol shown in Fig. .1.

In the drawing, in which similar kreference characters denote like parts in the various figness of the iluid drops is controlled so that drops of minimum size which, as a result of insumcient ures, A designates generally the pistol body vand B the spraying head attached thereon. The compressed air serving for the atomization passes through the bore `2'I in the handle 28. The quantity of air is regulated by the spring-actuated valve 25 which is actuated by the trigger 26. The air passes behind the valve through the bores -24 and 23 into the annular chamber I9.

The 'air passes from the annular chamber I9 through a plurality of bores 1 into another annular chamber I2.v The air jets subdivide therein and pass partly into the inner nozzle I, which is formed by the central members I3 and I4 and the surrounding member I5, and partly into the outer nozzle 2, which isformed by the surrounding member I5 and the outer housing I6.

vThe air serving for atomization passes iirst through the bores I0, the passages ofwhich may be modified or varied by means of the annular slide valve, Il. The latter is adjusted by rotating thev outer housing I6 by means of a tongue 22 attached to the annular slide and which engages in a helicall groove 35 of the housing I6.

-As a result of throttling the air by means of slide valve II a lower air velocity prevails in nozzle I `than in the outer nozzle 2. The air is uniformly distributed over the nozzle chamber by means of the rectifier 5, which consists of fine wire screening. Air meets the liquid at the liquid discharge opening l. Atomization begins at this point.

'Ihe air passing into the outer nozzle 2 is not throttled but merely distributed uniformly over the nozzle chamber by the rectifier 6.

The liquid to be atomized is 'passed from a pressure container through the passages into the spray head-B. Delivery to the liquid discharge point 4 takesplace through the bore'. The quantity of paint is regulated by the paint needle valve 3, which is opened forwardly by the trigger 26 through the plunger 29 and the lever 30. The latter acts against a housing 3| which is attached on the spindle 36 of the needlevalve 3 and is slidable in a guide 31 of the shank A. A spiral spring 32, the other end of which is applied against a housing 33 screwed in the shank A, acts against the housing'SI. For centering the needle valve 3, the bore 8 is provided with a guide member I8 provided with bores or p'assages 38 for the passage of the paint.

The liquid discharging at the point 4 comes uniformly in contact with the air passing over the periphery of the discharge cleft-and is atomof the atomizing jet at the point where the atomized thereby as a result of the prevailing relative l velocity. Atomization takes place within the inner nozzle I, in which a controlled air velocity is present. By suitable regulation of the air velocity thru the annular slide valve II the finepenetrative force, tending to form a mist, are

Ialmost entirely prevented from forming.

The outer nozzle 2, from which the air discharges at a greater velocity than from inner nozzle I, encompasses the latter nozzle. The mouth of inner nozzle I lies in the direction of flow in front of that of-outer nozzle l2.

The atomizing jet is designed to have a discharge velocity of between 60 and 140 meters per second while the depositing jet or driving'jet hasa considerably greater discharge yelocity.

Fig. 2 shows a different construction of the spray head B. In contrast to the case described relative to Fig. l, herefthe atomizing air for the inner nozzle I is taken from another source than that of the outer nozzle 2 intended for depositing t providing a controllable slide valve I'I, since the depositing air jet is taken from an air source having a higher pressure and which pass through the passages 34 directly into the outer nozzle 2 in which the rectifier 6 is located.

The outer nozzle 2 is formed by the surrounding member I5 and the outer housing I6. The passages for the paint] and 2i are constructed in the same manner as in the modilcationshown in Fig. 1.

I claim:

1. -A method of coating surfaces with liquids, particularly paints and lacquers comprising forming a liquid jet, an atomizing jet atomizing said liquid jet, a further driving jet acceleratingA said atomizing jet mixed with the atomized liquid whereby the discharge velocity of the'driving jet is considerably greater than the velocity izing jet meets the liquid jet.

2. A method of coating surfaces with liquids, particularly paints' and lacquers comprising forming a liquid jet, an atomizing jet atomizing said liquid jet, a further driving jet accelerating said atomizing jet mixed with the atomized liquid whereby the discharge velocity of the driving jet is considerably greater than the velocity of the atomizing jet at the point where the atomizing jet meets the liquid jet, this latter velocity of the atomizing jet being between 60 and 140 meters per second.

3. A method of coating surfaces with liquids particularly paints and lacquers comprising forming a liquid jet, an atomizing jet atomizing said liquid jet, a further driving jet accelerating said atomizing jet mixed with the atomized liquid whereby the discharge Velocity of the driv- 'ized liquid whereby the discharge velocity of the driving jet is considerably greater than the velocity ofthe atomizing kjet at the point wherethe atomizing jet meets the liquid vjet, this latter velocity of the atomizing jet being between 60 and 140 meters per` second, said driving jet concen- -trica1ly surrounding said atomizing jet.

5. A spray gun for coating surfaces with liquids particularly paints and lacquers comprising a liquid outlet means, a driving nozzle communieating with a compressed air conduit and forming a driving jet, an atomizing nozzle forming an atomizing jet, a communication between these two nozzles, a throttling means in said communication to diminish the velocity of the compressed air in said atomizing nozzle so that the velocity of theA unthrottled driving jet, discharging from the driving nozzle is considerably greater` than the velocity of the atomizing jet at the liquid outlet means, the liquid outlet being arranged within the atomizing nozzle, said atomizing nozzle being formed by a tube converging in the direction of the now, said driving nozzle surrounding the atomizing nozzle and converging in the direction of flow.

6. A spray gun for coating surfaces with liquids particularly paints and lacquers comprising a liquid outlet means, a driving nozzle communicating with a compressed air conduit, and forming `a driving jet, an atomizing nozzle forming an atomizing jet, a communication between these two nozzles, a throttling means in said communication to diminish the velocity of the compressed air in said atomizing nozzle so that the velocity of the unthrottled driving jet discharging from the driving nozzle'is considerably greater than the velocity of the atomizing jet at the liquid outlet means, Said throttlingmeans being controllable, the liquid outlet' means being arranged wlthin the atomizing nozzle, said atomizing nozzle being formed by a tube converging in the direction of the flow, saidl driving nozzle surrounding the atomizing nozzle and converging in the direction of iiow.

' charging from the driving nozzle is considerably greater than the velocity of the atomizing jet at the liquid outlet means, .the liquid outlet means being arranged within the atomizing nozzle, said atomizing nozzle being formedvby a tube converging in the direction of the flow, said driving nozzle surrounding the atomizing nozzle and converging in the direction of flow, a honey comb grid like ,'means located in the atomizing nozzle and working as a rectiiler for reducing the turbulence of the atomizing air and preventing rotational movement of the atomizing air in said atomizing nozzle, said rectifier being in the form of an annular screen.

9. Av spray gun for coating surfaces with liquids, particularly paints and lacquers comprising a liquid outlet means, a driving nozzle communicating with a compressed' air conduit and forming a driving je't, an atomizing nozzle forming an atomizing jet, a communication between these two nozzles, a throttling means `in said communication to diminish the velocity of the compressed air in said atomizing nozzle so that the velocity of the unthrottled driving jet, discharging from the driving nozzle is considerably greater than the velocity of the atomizing jet at the liquid outlet means, the liquid outlet means being arranged within the -atomizing nozzle, said atomizing nozzle being formed by a tube converging in the direction of the ow, said driving Y nozzle surrounding the atomizing nozzle and con- 7. A spray gun for coating surfaces with liquids ranged Within the atomizing nozzle, said atom^ izing nozzle being formed by a tube converging in the direction of the flow, said driving nozzle' surrounding the atomizing nozzle ad converging in the direction of flow, a honey comb grid like means located in the atomizing nozzle and working as'a rectifier for reducing the turbulence of the atomizing air and preventing rotational movement of the atomizing air in said atomizing nozzle.

8. A spray gun for coating surfaces with liquids, particularly paints and lacquers comprisling a liquid outlet means, a driving nozzle communicating with a compressed air conduit and forming a driving jet, an atomizing nozzle forming an atomizingV jet, a communication between these two nozzles, a throttling means in said communication to diminish the velocity of the compressed air in said atomizing nozzle so that loutlet of the atomizing nozzle and consisting ofv verging in the direction of flow, the liquid outlet means being controlled by a needle valve opening .towards the. discharge outlet of the atomizing nozzle and consisting of a double cone and a sliding shaft. i f

10. A spray gun for coating surfaces with liquids, particularly paints and lacquers comprising a liquid outlet means, a driving nozzle communicating'with a compressed air conduit and forming a driving jet, an atomizing nozzle forming an atomizingvjet, a communication between,

these two nozzles, a throttling means in said communication to diminish the velocity of the compressed air in said atomizing nozzle so that the velocity-of the unthrottled driving jet discharging from the driving nozzle is considerably greater than the velocity of the atomizing jet at the liquid outlet means, the liquid outlet means being arranged within the atomizing nozzle, said atomizing nozzle being formed by a tube converging in the direction of the flow, said driving nozzle surrounding the atomizing nozzle and converging in the direction of flow, a honey comb grid like means located in the atomizingnozzle and working as a rectifier for reducing the turbulence of the atomizing air and preventing rotational movement of the atomizing air in said atomizing nozzle, the liquid outlet means being controlled by a needle valve opening towards the discharge a double cone and a sliding shaft.

11. A spray gun for coating surfaces with liquids particularly paints and lacquerscomprising a chamber means provided with an opening constituting an atomizing nozzle, aliquid outlet means located within said chamber and spaced from said opening whereby the atomizing nozzle provides an atomizing jet, a driving nozzle surrounding said atomizing nozzle and formed by the outer wall of said chamber and a further wall spaced from said outer wall, a compressed air conduit; communicating with said driving nozzle to form a driving jet, communication the velocity of the unthrottled driving jet dismeans between said nozzles and throttling means in said communication means for diminishing the velocity of the compressed air in said atomizing nozzle so that the`velocity of the unthrottled driving jet discharging from said driving nozzle is greater than the velocity of said atomizing jet 'at said liquid outlet means.

12. A spray gun for coating surfaces with liquids particularly paints and lacquers comprising a chamber means provided with an opening constituting an atomizing nozzle, a liquid outlet means located within said chamber and spaced from said opening whereby the atomizing nozzle provides an atomizing jet, a driving nozzle surrounding said atomizing nozzle and formed by the outer wall of said chamber and a further wall spaced from said outer wall, a compressed air conduit communicating with said driving nozzle to form a driving jet, communication means between said nozzles and controllable throttling means in said communication means for diminishing the velocity of the compressed air in said atomizing nozzle so that the velocity of the unthrottled driving jet discharging from said driving nozzle is greater than the velocity of said atomizing jet at said liquid outlet means.

13. A spray gun for coating surfaces with spaced from said outer wall, a compressed airconduit communicating with said driving nozzle to form a driving jet, communication means between said nozzles and throttling means in said y communication means for diminishing the velocity of the compressed air in said atomizing nozzle so that the velocity of the unthrottled driving jet dischargingfrom said driving nozzle is greater than the velocity of said atomizing jet at said liquid outlet means and honey comb grid-like means located in the atomizing nozzle as well as in the driving nozzle and working as a rectifier for reducing the turbulence of the air and preventing rotational movement of the air in said atomizing nozzle and said driving nozzle.

14. A spray gun for coating surfaces with liquids particularly paints and lacquers comprising a chamber means provided with an opening 15. A spray gun for coating surfaces with liquids particularly paints and lacquers comprising a chamber means provided with an opening constituting an atomizing nozzle, a liquid outlet means located within said chamber and spaced from said opening whereby the atomizing nozzle provides an atomizing jet, a driving nozzle surrounding said atomizing nozzle and formed by the outer wall of said chamber and a further wall spaced from said outer wall, a compressed air conduit communicating with said driving nozsle to form a driving jet, communication means between said nozzles and controllable throttling means in said .communication means for diminishing the velocity of the compressed air in said 'atomizing nozzle so that the velocity of the unthrottled driving jet discharging from said driving nozzle is greater than the velocity of said atomizing jet at said liquid outlet means and a honey comb grid-like means located in the atomizing nozzle and working as a rectiiler for reducing the turbulence ofthe atomizing air and preventing rotational movement of the atomizing air in said atomizing nozzle.

16. A spray gun for coating surfaces with liquids particularly paints and lacquers comprising a chamber means provided with an opening constituting an atomizing nozzle, a liquid outlet meanslocated within said chamber and spaced from said opening whereby the atomizing nozzle provides an atomizing jet, a driving nozzle lsurrounding said atomizing nozzle and formed rbetween said nozzles and controllable throttling A means in said communication means for diminishing the velocity of the compressed air insaid atomizing nozzle so that the velocity of the un- .throttled driving jet discharging from said driving nozzle is greater than the velocity of said constituting an atomizing nozzle, a liquid outlet means located within said chamber and spaced from said opening whereby the atomizing nozzle provides an atomizing jet, a driving nozzle surzle to form a driving jet, communication means` between said nozzles and throttling means in said communication means for diminishing the velocity oiV the compressed yair in said atomizing nozzle so that the velocity of the unthrottled driving jet discharging from said driving nozzle is greater than the velocity of said atomizing jet at said liquid outlet means and honey comb grid.

like means located in the atomizing nozzle as well as in the driving nozzle and working as a rectifier for reducing the turbulence of the air and preventing rotational movement of the air in said atomizing nozzle and said driving nozzle, said rectiers being in the form of annular screens.

atomizing jet at; said liquid outlet means and a honey comb grid-like means located in the atomizing nozzle and working as a rectiiierfor reducing the turbulence of the atomizing air and preventing rotational movementof the atomizing air in said atomizing nozzle, said rectier being in the form of an annular screen.

17. A spray gun for coating surfaces with liquids particularly paints and lacquers comprising a chamber means provided with an opening constituting an atomizing nozzle, a liquid outlet means located within said chamber and spaced from said opening whereby the atomizing nozzle provides an atomizing jet, a driving nozzle surrounding said atomizing nozzle and formed by the outer wall of said chamber and a further wall spaced from said outer wall, a compressed air conduit communicating with said driving nozzle to form a driving jet, communication means between said nozzles and controllable throttling means in said communication means for diminishing the velocity of the compressed air in said atomizing nozzle so that the velocity of the unthrottled driving jet discharging from said driving nozzle is greater than the velocity of said atomizing jet at said liquid outlet means and a honey comb grid-like means located in the atomizingnozzle as well as in the driving nozzle and working as a rectiiier for reducing the turbulence of the air and preventing rotational movement of the air in said atomizing nozzle and in said driving nozzle,

18. A spray gun for coating surfaces with*- liquids particularly paints and lacquers comprising a chamber means provided with an opening constituting an atomizing nozzle, a liquid outlet means located `within said chamber and spaced from said opening whereby the atomizing-nozzle provides an atomizing jet, a driving nozzle s urrounding said atpmizing nozzle and formed by the outer wall of said chamber and a further wall spaced from said outer wall, a compressed air conduit communicating with said driving nozzle to form a driving jet, communication means between said nozzles and controllable .throttling means in said communication means for diminishing the velocity of the compressed air in said atomizing nozzle so that the velocity of the unthrottled driving jet discharging from said driving nozzle is greater than the velocity of said atomizing jet at said liquid outlet means and a honey comb grid-like means located inV the atomizing nozzle as well as in the driving nozzle and working as a rectifier for reducing the turbulence of the air and preventingA rotational movement of the air in said atomizing nozzle, and said driving nozzle, said rectiers being in the form of annular screens. y

19. A spray gun. for coating surfaces with liquids particularly paints and lacquers comprisl ing a chamber means provided with an opening constituting an atomizing nozzle, a. liquid outlet means located within said chamber and spaced from said opening whereby the atomizing nozzle provides an atomizing jet, a driving nozzle surrounding said atomizing nozzleand formed by the outer wall ofV said chamber and a-'Iurther wall spaced from said outer wall, a compressed air conduit communicating with said driving nozzle to form a driving jet, communication means between said nozzles and throttling meansin said communication means for diminishing the velocity of the compressed air in said atomizing nozzle so that the velocity of the unthrottled driving jetdischarging from said driving nozzle is greater than the velocity of said atomizing jet at said liquid outlety means and a honey comb grid-like means located in theatomizing nozzle and working as a rectier for reducing the turbulence of the atomizing air and preventing rotational-movement of theatomizing air in said atomizing nozzle.

20. A spray gunv for coating surfaces with liquids particularly paints and lacquers comprising a chamber means provided withfan opening constituting an atomizing nozzle, a liquid outlet means located within said -chamber and spaced from said opening whereby` the atomizing'nozzle s'aid communication means for diminishing the.

velocity of the compressed air in said atomizing nozzle so that the velocity of the unthrottled driving jet discharging from said driving nozzle is greater than the velocity of said atomizing jet at saidliquid outlet means and a needle valve controlling said liquid outlet means, said needle valve opening towards the discharge outlet of said atomizing nozzle and comprising -a double cone and a sliding shaft'.

M mrscno PoPorF. 

